1. Field of the Invention
The present invention relates to improvements in duplex copying units, which can be optionally and detachably mounted upon an image forming apparatus, for example, a copier, facsimile machine, printer, etc.
2. Description of the Related Prior Art
In a conventional image forming apparatus, a duplex copying unit can be optionally attached/detached thereto, since a user does not always need the duplex copying function. The duplex copying unit receives a sheet having an image or printing on one side thereof, and returns the sheet to the inlet of the image forming apparatus, so that two-sided printing or copying can be achieved. In the case where the duplex unit is utilized it is detachably mounted upon the image forming apparatus. However, problems can arise with regard to which part or location at which the duplex unit should be attached. In particular, in the conventional image forming apparatus, there is provided an operation key, by which a predetermined copy mode is set, and/or an operation board, on which, for example, a copying number is displayed, at a front side of the body of the image forming apparatus. In such device, if a duplex copying unit is attached over the operation key and/or an operation board, it is difficult for the operator to view or have access to the operation key and/or an operation/display board.
One conventional image forming apparatus, for example, as disclosed in the specification of the Japanese Laid Open Patent Publication Number 60-209745/1985, resolves the above problems. If a duplex copying unit is attached to the image forming apparatus covering the operation key and/or a operation board, it is moved to a position where the operator can see it more easily. However, in such a device the it is still difficult for the operator to see the operation panel from a place remote therefrom, for example, from a host-computer to which the above-mentioned image forming device is connected.